The rust inside this kettle shows an emergent pattern that is typical of the self-organising dynamics of reaction-diffusion systems.

One example of self-organising dynamics is in the topographic map of ocular dominance columns in the visual cortex. These intricate maps display a fascinating combination and interplay of regularity and irregularity. Such patterns have been modelled by computational neuroscientists using the Kohonen algorithm and variants

Thanks for the picture Cat!